feat: support Pubky signup

[ben-kaufman]

Description

• Accept app-authorized pubkyring://signup and auth-bearing pubkyauth://signup requests, plus direct pubkyauth://direct_signup and parameter-only legacy pubkyauth://signup, through the normal scanner and deep-link flow.
• Register the wallet-derived Pubky identity with the requested Homeserver and optional signup token.
• Require explicit approval and the existing PIN/biometric check for every signup format; show the requested homeserver before registration.
• Restore locally owned identities by signing in on their existing homeserver, keeping credentials retryable after failures instead of registering at Homegate.
• Activate the returned Paykit session and continue into the existing profile setup flow.
• Reuse the approval sheet’s loading state while signup completes, report Already signed in when a local identity exists, and keep payment-only scanner state intact when rejecting Pubky requests.

This PR is stacked on #1200 and uses its Paykit rc51 authorization model. Ordinary Pubky App sign-in must use that grant-auth model; compatibility with the older sign-in request is intentionally outside this signup PR.

Preview

Not included; this reuses the existing scanner, authorization approval sheet, loading treatment, and profile setup UI.

QA Notes

1. With no Pubky identity, scan a signup QR from staging Pubky App; approve it, confirm the website continues, and complete profile setup.
2. With no Pubky identity, scan either direct signup format; confirm the homeserver is visible, Cancel performs no registration, and Authorize requires local authentication before profile setup opens.
3. Scan a signup request while signed in and confirm the Already signed in state.
4. Confirm payment-only scanners reject Pubky requests without clearing the current payment flow.
5. With the wallet locked, open a signup deep link; confirm nothing registers or opens until unlocking, then the approval sheet appears.
6. After signup on a non-default homeserver, make session recovery fail, restore connectivity, and retry Create/Restore Profile. Confirm it keeps the same homeserver. Repeat with a failed profile save and confirm retry never calls signup.

Validation:

• Full testDevDebugUnitTest: 2,346 tests passed on the restacked branch.
• compileDevDebugKotlin and detekt passed.
• Regression coverage includes locked signup deep links, consent/local-auth ordering, real SDK activation and partial-persistence cleanup, stale pending state, and one-time profile navigation.
• PubkyRepoTest.kt: 97 tests passed, including existing-key recovery, secure-storage errors, sign-in/profile failure retries, cancellation, and no-key signup. Detekt reports no changed-file findings.

[greptile-apps]

Greptile Summary

This PR adds Pubky Ring signup URL parsing and scanner routing, registers the wallet-derived identity with the requested Homeserver, activates Paykit, and resumes profile setup through durable local state.

• Adds parsing and validation for pubkyring://signup requests.
• Adds registration, requester authorization, session activation, and profile-setup continuation.
• Preserves payment scanner state when Pubky requests are rejected and reports existing local identities.

Confidence Score: 3/5

This PR should not merge until signup activation can recover from the second network operation failing and pending profile setup can be exited without an immediate navigation loop.

The new signup sequence can complete remote registration and authorization while leaving Bitkit without a local session, and the successful path's durable pending marker makes the CreateProfile back action ineffective.

Files Needing Attention: app/src/main/java/to/bitkit/services/PaykitSdkService.kt, app/src/main/java/to/bitkit/repositories/PubkyRepo.kt, app/src/main/java/to/bitkit/ui/ContentView.kt

Important Files Changed

Filename	Overview
app/src/main/java/to/bitkit/models/PubkyAuthRequest.kt	Adds strict Ring signup parsing, query validation, and conversion into the existing Pubky authorization request model.
app/src/main/java/to/bitkit/repositories/PubkyRepo.kt	Coordinates signup registration, authorization, activation, and pending profile state, but the multi-step flow can strand remotely completed signup without a local session.
app/src/main/java/to/bitkit/services/PaykitSdkService.kt	Adds registration without activation, discarding an activatable signup result and requiring a failure-prone second sign-in.
app/src/main/java/to/bitkit/viewmodels/AppViewModel.kt	Routes Ring signup through the normal scanner while explicitly rejecting Pubky requests in payment-only contexts.
app/src/main/java/to/bitkit/ui/ContentView.kt	Resumes pending profile setup automatically, but conflicts with the unchanged dismissible CreateProfile back action.
app/src/main/java/to/bitkit/ui/screens/profile/PubkyAuthApprovalViewModel.kt	Dispatches Ring signup approval, handles existing identities, and dismisses the approval sheet before profile setup.

Sequence Diagram

sequenceDiagram
    participant Scanner
    participant Approval as Approval UI
    participant Repo as PubkyRepo
    participant Server as Homeserver
    participant App as Requesting app
    participant Paykit
    Scanner->>Approval: Pubky Ring signup request
    Approval->>Repo: Approve signup
    Repo->>Server: Register derived identity
    Repo->>App: Approve authorization
    Repo->>Paykit: Sign in and activate session
    Paykit-->>Repo: Active local session
    Repo-->>Approval: Dismiss approval
    Repo->>Repo: Mark profile setup pending
    Repo-->>Scanner: Navigate to profile setup

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_{Reviews (1): Last reviewed commit: d02c926 | Re-trigger Greptile}

[ben-kaufman]

@jvsena42 Fixed this. Pubky auth links now enter the scan queue before the cached Paykit flag is ready. The scan reads the persisted setting before routing, so the cold-start path no longer drops the link while disabled Paykit and missing-wallet cases still stop.

[jvsena42]

@ben-kaufman conflict

[github-actions]

Regtest APK

Built from 6b27371 (run).

Download bitkit-dev-debug universal APK (expires in 30 days).

[jvsena42]

✅ Approved with some observations

• ✅ On Loopky -> Click on sign in with ring -> selected Bitkit (with a Pubky identity) -> Authorize
• Could not test sign in on Pubky-ring 1.19 because of pubky/pubky-ring#375 . We can revisit the feature when the issue is fixed

addressed - manually confirmed

[ovitrif]

Merging with bypass rules, I can't find this easily, it might be in the collapsed sections